The predominant use of the "paralleling" technique in dental radiography results in low distortion exposures if the film packet can be properly placed within the patient's oral cavity. For periapical radiographs, the film placement must be sufficient to enable an exposure of the entire tooth including the crown and root and as much of the tissues surrounding the root as possible. This requirement, coupled with the need to maintain the film in a plane parallel to the long axis of the teeth, causes significant problems. There are currently two types of film packets. One type consists of a stiff cardboard-like paper packet. Another is a plastic packet which is heat sealed around its perimeter. This seal provides a thinner, more flexible edge. However, the plastic edge is even more sharp than that of the paper packet. Both forms therefore cause discomfort and often fairly intense pain when pressed into tissues by a dental operator attempting to obtain an adequate exposure. This is particularly difficult with children, adults with small mouths, and adults who exhibit sensitive bony projections off of the inside of the mandible and the hard palate, known as tori. It is especially difficult when the patient is required to cooperate in holding the film packet in the desired position by biting firmly on a film holder. Children will often not cooperate due to the pain and discomfort caused from the film packet. However, if the film packet is allowed to shift within the patient's mouth to a more "comfortable" position, or if the patient will only bite until the film meets resistance with his soft tissue, the quality of the resulting radiograph will be adversely effected.
This problem has not, to the knowledge of the present applicant, been adequately solved until advent of the present invention.
Pads for radiographic film have been disclosed in prior patents. For example, U.S. Pat. No. 1,995,579 to M. B. Hodgson discloses an X-ray dental film package that includes an absorbent pad structure attached to one surface of the film package and extends across the surface to a perimeter enclosing the entire perimeter of the film packet. The problem of discomfort was therefore recognized by Hodgson. However, the solution disclosed, while adequate for some purposes, added a considerable amount of bulk to the film package and therefore added to the difficulty in obtaining properly exposed radiographs. It is noted also that the "bisecting" method of obtaining radiographs was then in popular use. This technique allowed placement of the film packets at more comfortable angular orientations within the patient's mouth. The Hodgson package may therefore have functioned adequately with this particular radiographic technique, but cannot be adequately used with the currently more popular diagnostically accurate "paralleling technique". This is due primarily to the fact that the absorbent pad increases the overall thickness of the film package considerably and the peripheral rim extends the overall packet dimensions also by a considerable amount. Furthermore, the pad is constructed of "pressed absorbent cotton". This material will increase comfort to the patient but will not compress significantly when pressed against the soft tissues of the sublingual mucosa below the patient's tongue or the hard or soft palate above the tongue.
U.S. Pat. No. 1,537,925 to Bolin discloses a dental X-ray film package. Here, the package itself has been modified to include a yieldable package having a thick perimeter "bead". The pack is formed of an elastic rubber and the peripheral "beading" extends about the entire film perimeter. This package, like the Hodgson arrangement, includes an overall length and width dimension substantially greater than the actual film size. This results in problems similar to those discussed above.
A partial solution to the film packet size problem is recognized in U.S. Pat. No. 1,631,497 to Marler. Marler discloses a resilient bead arrangement for encasing the perimeter of a film packet. The improvement is in the elimination of an additional surface formed integral with the bead as shown in Bolin and Hodgson. Marler, however, continues use of the bead extending about the entire package periphery.
U.S. Pat. No. 2,084,092 to Kenney discloses a dental film holder. This holder is provided primarily for the purpose of providing a "bite wing" for gripping between the patient's teeth to produce "bite wing" exposures. This is a form of exposure often used for detecting interproximal caries. Bite wing X-rays do not require exposure of the root tips and surrounding tissues as with periapical exposures. The holder is formed of a resilient material with corner pockets to receive adjacent corners of the film packet. All four corners of the film packet are received within adjacent pockets of the holder which thereby increase the overall film packet size. Furthermore, sections of the sharp film packet edges are left exposed and can engage tissues to cause discomfort during exposure.
The problem of affording adequate padding along the relatively sharp edges of intraoral radiographic film packets has remained, until advent of the present invention. The present invention can be utilized to cushion the engaged tissues of the patient against the sharp edges of a film packet while maintaining a minimal overall film dimension. These two features enable very accurate and complete exposures using the paralleling technique while also maximizing patient comfort.